Heat transfer unit



Sept. 16,1947. J.,ASK|N 2,427,336

' HEAT TRANSFER UNIT Filed A ril 25, 1945 Patented Sept. 16, 1947 HEAT TRANSFER UNIT Ind., assignor to Peerless Joseph Askin, Marion,

of America, Inc., Chicago,

of Illinois 7 111., a corporation Applicatlon April 25, 1945, Serial No. 590,237

The invention relates to heat transfer units. In heat transfer units, such as condensers for a refrigerant, it has been found advantageous to form a coil through which fiuid passes for heat transfer from a single length of tubing with integral bends at the ends and parallel members between the bends and to use sheet metal finforming strips through which the tubing extends for heat transfer from the tubing.

One object of the invention is to provide a coil of this type with fin-forming strips through which a series of parallel tubing-members extend, and in which said members are secured with con tacting areas between the fin-strips and the tubing for efficient heat transfer.

Another object of the invention is to provide a heat transfer unit which comprises a coil of tubing with integral bends at its ends and intermediate connecting-members between the bends which, in cross-sectional contour, are deformed for efllcient heat transfer from the fluid passing through'the tubing to fin-Strlps having surfaces contacting with and conforming to the deformed tubing.

A still further object of the invention is to provide a heat transfer unit which comprises tubing having substantially parallel members serially connected by integral bends and fin-forming sheet metal strips which is simple in construction, can be produced at low cost, and is efficient in heat transfer.

Other objects of the invention will appear from the detailed description.

1 Claim. (01. 257-262) and outlet l3 are, in cross-section, deformedto increase the rate of flow of the fluid between said bends. Each tube-member ID, in cross-section, has a portion I5 curved on a relatively large radius, an oppositely disposed portion l6 which is curved on a smaller radius, and substantially straight convergent side-portions l'l opposite the differently curved portions. The bends II are cylindrical in cross-section.

The tubing-members Ill extend through a series of strips i8 which are formed of sheet metal having a. high coefiicient heat conduction. Each strip has a seriesfof openings which conform series of said tubing-members.

to the cross-sectional contour of tube-members it and extends transversely across the entire Each strip I8 is formed around a portion of each hole 20 with an integral flange il extending transversely to the plane of the strip'and longitudinally of the tubing-members Ill. These flanges 2i conform to and fit around the convergent side portions i1 and the curved portion 16 which is formed on a curve of lesser diameter than the longitudinally curved portion I5 0n the opposite side of the tubing. Each fin-strip i8 is also formed with integral arcuate flanges 22 which project transv versely from the plane of the strip and. extend The invention consists in the several features Fig. 1 is a side elevation of the heat transfer 1 unit embodying the invention.

Fig. 2 is an end view.

Fig. 3 is a perspective on an enlarged scale of one of the fin-strips and a portion of the coil.

Fig. 4 is a perspective of a portion of the finstrip which is provided with openings into which the tubing may be placed before the strips are bent to secure the tubing in the strips.

The invention is exemplified in a heat transfer unit, for example, a condenser which comprises a coil of tubing which is formed of a continuous length of stock bent to form a series of parallel tube-members Ill connected by 180 integral bends II. The ends of the tubing, as at 12 and i3 provide connections for inlet and outlet pipes for the fiuid, such as a refrigerant gas. The parallel tube-members l0 between bends ii, and inlet 62 longitudinally of and conform to opposite sides of curved portion l5 of the tubing which is curved on the greater diameter. The strips 18 may be formed with an offset rib IQ for stiffening them. This cross-sectional contour of coil-members Ill produces low frictional resistance to and increases the velocity of the gas in transit through said members, for improved heat conduction. After assembly of the strips and tubing in this manner, they are bonded together by soldering or brazing. This may be done by dipping the unit in'solder which causes the solder to be held by capillary attraction in the corners of the joints between the strips, draining the other solder from the unit and the plates including the meeting edges of the portions 27. The tubing and strips may also be copper-plated and bonded together by hydrogen brazing.

In order to permit the coil of tubing to be assembled and extend through strips l8, each strip is split as at 26 between the openings 20 therein and one edge of the strip to render the porentisz gagement with the convergent side portions l1 and the curved portion [6 of the tubing. Flanges 22, after the split portions 01 the strips are bonded together, provide increased contact area.

'7 and firm contact between the strips I I and the curved portion I5 oi the tubing. In the assembled unit, the metal in portions 2'! will close the openings in the strips 18. The heat transfer is improved by virtue 01 having a greater amount of indirect surface as well as by virtue of an increase in contact between the direct and indirect surfaces.

The unit may be fabricated according to the method set forth in an application filed by me on April 25, 1945, serially numbered 590,238.

The invention exemplifies a heat transfer unit which comprises a coil formed of a single length of tubing and tin-strips adapted for eflicient heat transfer from the tubing which is efllcient in operation, is composed of few parts, and may be produced at low cost.

The invention is not to be understood as limited to the details described, since these may be modified within the scope of the appended claim without departing from the spirit and scope of the invention.

Having thus described the invention. what I claim as new and desire to secure by Letters Pat- A heat transfer unit comprising a coil of tubing having a series of integral parallel portions connected by integral bends, the bends being cylindrical in cross-section, the parallel portions of the tubing having in cross-section oppositely disposed portions, one of which is curved on a greater radius than the other and substantially flat convergent portions between the curved portions, and one-piece fin strips, of sheet material having a series of openings through which the parallel portions of the tubing extend and conforming to said cross-sectional contour of the parallel portions, splits extending from the portions of the openings fitting the portions of the greater radius to one edge 01 the strips through which the parallel portions of the tubing can be inserted transversely into the openings, arcuate flanges on the portions of the strips extending around the portions of the tube having the greater radius and flanges each conforming to the flat convergent portions and the curved portions having lesser radius of the tubing.

JOSEPH ASKIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 'Great Britain Aug. 24, 1933 

